Intramedullary nails are considered to be effective for internal fixation in the treatment of fractures, etc.; and recently, the use of such nails has become common. Specifically, in this method, the intramedullary nail is inserted into the bone marrow through the fracture site, and internal fixation is accomplished by passing at least two transfixation screws through screw holes formed in the intramedullary nail on both sides of the fracture site. In this method, however, depending on the location of the fracture, there may be cases in which the transfixation screws do not pass through.
Meanwhile, the destruction of the ankle joint is also common in patient with rheumatoid arthritis, etc. In such cases, arthrodesis of the ankle joint is considered to be effective. However, arthrodesis of the ankle joint is extremely difficult. Therefore, there are several conventionally utilized methods to fix these joints, and these include the following: 1) Methods in which cancellous screws are passed obliquely through the tibia and screwed into the talus or calcaneus. 2) Methods in which a plate is positioned along the talus, tibia and/or calcaneus and fixed using screws. 3) Methods in which pins are inserted in the tibia, talus and/or calcaneus, and then fixed to an external fixation device.
However, one problem that is common to these methods is that fixation is not rigid. In particular, they do no sufficiently control rotation and bending of the ankle joint. As a result, long period of immobilization without weight-bearing is required after surgery. Furthermore, in cases where an external fixation device is used, the pin insertion areas tend to become contaminated, so that repeated dressings is required.
Meanwhile, arthrodesis of the ankle joint, the use of conventional intramedullary nails is also considered. However, even if used in combination with transfixation screw, intramedullary nails do not sufficiently control rotation, pronation and supination, and dorsal and plantar flexion of the ankle-joint, particularly in patients with rheumatoid arthritis who have osteoporotic bone.
The present invention solves such problems. In short, the object of the present invention is to provide an intramedullary nail which makes it possible to obtain a firm fixation and which can easily perform operation.